1. Field of the Invention
The present invention relates, in general, to tubular-type door locks with indoor and outdoor handles and, more particularly, to a device for unlocking such a tubular-type door lock in conjunction with the indoor handle, the unlocking device quickly and simultaneously performing both a door latch opening action and an unlocking action in conjunction with a rotating motion of the indoor handle, thus allowing a user to easily and quickly open a door by rotating the indoor handle without separately unlocking the lock.
2. Description of the Prior Art
As well known to those skilled in the art, door locks are typically classified into two types: cylinder-type locks and tubular-type locks. The typical cylinder-type door locks are designed as follows. That is, when the indoor locking button of a cylinder-type lock is pressed to lock the door, it is impossible to operate the outdoor handle without using a key. Therefore, the lock with the pressed indoor locking button cannot be unlocked outside the door if a user does not use a key. However, in such a case, the indoor handle is rotatable, so that a user can unlock and open the door by rotating the indoor handle.
Meanwhile, tubular-type door locks are designed so that when the lock is locked by rotating an indoor locking lever, neither the indoor handle nor the outdoor handle of the lock can be operated if a user does not use a key. Therefore, when it is necessary for a user to open a door with a tubular-type door lock being locked by the locking lever, the user has to unlock the door lock prior to operating the indoor handle. The tubular-type door locks are thus inconvenient to users.
In order to overcome the above-mentioned problems, a tubular-type door lock with a somewhat improved structure is proposed. The above lock is designed as follows. That is, when the lock is locked by rotating an indoor locking lever, the indoor handle is operable with the locked state of the lock being maintained, while the outdoor handle is not operable if a user does not use a key. Since the locked state of the lock is maintained even though the indoor handle is operated by a user, such locks sometimes render users puzzled. That is, some users may open the door by rotating the indoor handle and go out of a room without unlocking the locking lever or having the key of the lock. In such a case, the door lock cannot be unlocked outside the door, thus forcing the user to send for a locksmith while paving charges for such services. It is thus necessary for users, wanting to be free from such mistaken conditions, to always confirm the locked or unlocked position of the locking lever at a time he goes out of a room and this is an inconvenience to the users.